The present embodiments relate generally to apparatuses and methods for providing a service path through and sealing between structural members within a turbine engine. More specifically, but not by way of limitation, present embodiments relate to apparatuses and methods for providing a sealed service pathway between the bosses within a turbine engine while still allowing relative movement between thermally isolated structural members.
In the turbine engine, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. These turbine stages extract energy from the combustion gases. A high pressure turbine includes a first stage nozzle and a rotor assembly including a disk and a plurality of turbine blades. The high pressure turbine first receives the hot combustion gases from the combustor and includes a first stage stator nozzle that directs the combustion gases downstream through a row of high pressure turbine rotor blades extending radially outwardly from a first rotor disk. In a two stage turbine, a second stage stator nozzle is positioned downstream of the first stage blades followed in turn by a row of second stage turbine blades extending radially outwardly from a second rotor disk. The stator nozzles turn the hot combustion gas in a manner to maximize extraction at the adjacent downstream turbine blades.
The first and second rotor disks are joined to the compressor by a corresponding rotor shaft for powering the compressor during operation. The turbine engine may include a number of stages of static air foils, commonly referred to as vanes, interspaced in the engine axial direction between rotating air foils commonly referred to as blades. A multi-stage low pressure turbine follows the two stage high pressure turbine and is typically joined by a second shaft to a fan disposed upstream from the compressor in a typical turbo fan aircraft engine configuration for powering an aircraft in flight.
As the combustion gasses flow downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced. The combustion gas is used to power the compressor as well as a turbine output shaft for power and marine use or provide thrust in aviation usage. In this manner, fuel energy is converted to mechanical energy of the rotating shaft to power the compressor and supply compressed air needed to continue the process.
In oil sump subassemblies, for example, of turbine engines, air gaps must be provided to compensate for thermal stresses and operating loads of the turbine engine. However, various pathways and passages are formed within the subassembly members for services such as pressurized air, cooling air, oil flow and others. Some of these frame member subassemblies have boss features adjacent the air gaps. The air gaps create areas of leakage hindering the services of the turbine engine.
For example, hot sumps may utilize contain service tubes that bridge between radially inner and outer walls of the subassembly members. Due to the high temperatures and thermal stresses in this area of the engine, often times these outer walls, inner walls and tubes need to be thermally isolated from one another.
An apparatus is needed which allows use of a service tube to seal across two regions of temperature and/or pressure differential, for example between a hot outer wall and a cooler inner wall while maintaining a thermally isolated system.
As may be seen by the foregoing, there is a need a service tube which may be sealed to create a path across a gap. Additionally, there is a need to provide for relative movement within the system due to thermal growth or expansion of members at different rates.